Rapid advances in semiconductor technology, particularly in the trend toward sub-micron geometry, have resulted in greater sensitivity of packaged semiconductor devices to damage from electrostatic discharge. Protecting advanced semiconductor devices against electrostatic discharge during shipping and handling is essential to maintaining high reliability. Such protection is often expensive and frequently becomes a significant factor in the cost of the semiconductor device.
Conventionally packaged integrated circuits (e.g., semiconductor dual-in-line plastic and ceramic packages each having a pair of parallel rows of conductors protruding from a package in which an integrated circuit is housed) are shipped in tube-shaped containers often called DIP tubes (tubular containers). Typically, these DIP tubes are made up of extruded polyvinyl chloride (PVC) or other extrudable material. The DIP tubes protect the packaged circuits against damage or contamination during shipping and handling. The internal shape of the tubular containers are typically selected so as to facilitate the use of efficient and convenient handling procedures. For example, with dual-in-line packages, the inside of the tube containers might have a hump-like structure over which the packages can slide, Such a structure permits the use of convenient handling procedures and permits mechanical handling of the packages. Also, the tubular containers are quite inexpensive and can be reused.
However, for packaged integrated circuits that are sensitive to electrostatic discharge, these DIP tubes do not provide sufficient protection against damage from electrostatic discharge.
Some electrostatic protection is provided by the use of conductive plastic in the manufacture of shipping containers. This type of electrostatic protection has certain advantages. For example, since the DIP tubes have the same shape as conventional containers, the same handling procedures can be used as with DIP tubes. However, conductive container structures often do not provide adequate protection for circuit packages that are extremely sensitive to electrostatic discharge. In addition, there may be abrasion between the dual-in-line packages and the conductive plastic of the tubular container which can result in particulate contamination. This may cause a reliability problem with electro-optic or imaging integrated circuits.
Better electrostatic protection is provided by inserting the pins of the packaged integrated circuit into conductive foam to provide direct electrical contact between the pins. A packaged circuit is inserted into conductive foam and then the combination is put into a box (container) for shipping and handling. Although this type of shipping container provides excellent protection against damage from electrostatic discharge, handling procedures are much less convenient principally because the circuit package must be individually lifted out of the conductive foam and the circuit package can not be inserted into or removed from the shipping box by sliding along a rail. Also, conductive foam is expensive and the cost of this type of shipping and handling container is significantly higher than the conventional tubular container. In a technology where price competition is very great, higher costs for containers is highly disadvantageous.
A number of references disclose containers for handling small sensitive electronic components. Particularly relevant is U.S. Pat. No. 4,382,509 (Bertram I. Gordon), issued May 10, 1983, which discloses a container made up of cardboard having a conductive metallic coating on the surface. The container has a portion (i.e., a hump or rail) on which electronic components are securely placed so that the pins or connecting lugs protrude from the electronic component are all electrically interconnected by the metallic coating. Electrical interconnection of the pins or lugs by the metallic coating prevents build-up of static electricity which might damage the electronic component. Although this type of container protects against damage from static electricity, the electronic components do not slide along the hump or rail which makes handling much less convenient and precludes mechanical handling. Also, the abrasion between pins and hump often damages the circuit packages and causes contamination of the circuit packages. In addition, the conductive metallic coating and the metallic clips used to close the container makes the cost of the container relatively high considering the competitive nature of the semiconductor device field.
U.S. Pat. No. 4,706,161 (John S. Buckingham), issued Nov. 10, 1987, discloses a protective apparatus for electrical devices having coplanar leads which provides both mechanical and electrostatic discharge protection. The protective apparatus is essentially a socket and carrier type device with circuit chips mounted on a ceramic substrate. Although affording excellent mechanical and electrostatic protection, the protective device is relatively expensive and does not lend itself to easy handling of the protected electronic devices.
U.S. Pat. No. 4,564,880 (Allen E. Christ et al.), issued Jan. 14, 1986, discloses a carrier for integrated circuits having uniform conductivity and an arrangement to securely hold the integrated circuit in a predetermined position within the carrier. The carrier includes a hinge arrangement and a latching system. This carrier is relatively expensive, and because the integrated circuit is securely held in place, it does not lend itself to easy handling of the packaged circuits contained in the carrier. The integrated circuit package carrier disclosed in U.S. Pat. No. 4,615,441 (Ryuichi Nakamura), issued Oct. 7, 1986, has similar limitations.
U.S. Pat. Nos. 4,815,596 (Steven J. Reid), issued Mar. 28, 1989, discloses a circuit component carrier useful for housing a single dual-in-line integrated circuit package. The carrier comprises a box-like shell and cover which are hinged together. The shell comprises a rectangular bottom wall and side walls forming a receptacle. Projecting from the bottom wall and into the shell are spaced walls adapted to fit between the dual rows of pin on the circuit package. The carrier is molded from an electrically conductive polymeric composition, typically a polyallylomer loaded with carbon particles. This carrier is expensive and accommodates only one circuit package for each carrier. Also, the design does not permit easy handling of the components being carried.
Similar limitations exist for containers disclosed in two other references, namely, U.S. Pat. No. 4,241,829 (Charles T. Hardy), issued Dec. 30, 1980, and U.S. Pat. No. 4,585,121 (Ernest A. Capelle, Jr.), issued Apr. 29, 1986. The Hardy patent discloses a container useful for handling and shipping of electrostatic sensitive electronic components made up of a box-like carton with interior and exterior surfaces coated with conductive material. A liner of convoluted foam impregnated with a conductive material is secured to the interior surfaces of the lid and the bottom of the box-like carton, the impregnated conductive material forming a continuous conductive path with the conductive coating. This container does not lend itself to easy and convenient handling of the packages stored therein since each individual package must be inserted and removed from the container. Also, the containers are quite expensive. The Capelle, Jr. patent discloses a container for storing and handling multichip hybrid packages during manufacture, testing and inspection. The receptacle and cover are recessed to receive a wide range of component sizes and shapes. The container is made of electrically conductive, high temperature resistant carbon plastic for protection from electrostatic discharges and environmental temperature chamber testing. The container only affords limited protection against damage from static electricity and is designed largely to observe electronic devices during testing.
U.S. Pat. No. 3,774,075 (Alfred L. Medesha), issued Nov. 20, 1973, discloses a package for storage and shipping of electrical equipment in which the package includes an element for shorting the electrical equipment. The patent describes a tubular short circuiting part made of conduction material for temporarily holding integrated circuits immediately after removal from the shipping package and before incorporation into electrical equipment.
Various shipping containers made in the form of tubes useful for shipping static-sensitive electrical components are known. These tubes are typically made of electrically conductive material. For example, U.S. Pat. No. 5,014,849 (Raymond P. Becker), issued May 14, 1991, discloses a shipping tube made of a laminate of paperboard and layers of electrically conductive material on both the inner and outer surface of the paperboard. End caps used therein are also made of conductive material.
U.S. Pat. No. 4,565,288 (Albert Walther), issued Jan. 21, 1986, discloses a tubular container for holding semiconductor components in which guides are provided to prevent contact of the components to the tubular container. In one embodiment, the guides are conductive which reduces electrostatic problems. However, because of abrasion between the guides and the package pins during loading, the loading process often causes damage to the package and introduces contamination to the container. U.S. Pat. No. 4,463,851 (Waldo E. Cecil), issued Aug. 7, 1984, discloses a protective enclosure for electronic devices which includes a tube formed from conductive polyvinyl chloride and comprising a bottom wall, side walls and a top wall.
U.S. Pat. No. 4,590,534 (Yoshihiro Akamatsu et al.), issued May 20, 1986, describes a tube-like container for integrated circuits made from laminated sheet with extremely thin (30 to 200 Angstroms thick), transparent conductor covered with plastic. This provides a conductive shield around the circuit package which acts as an electrostatic shield but does not provide electrical contact to the package pins. The inside of the tube is shaped so as to accommodate a dual-in-line semiconductor package. These containers are expensive and often do not provide adequate protection against damage from electrostatic discharge.
A number of references disclose flatpack-type packages and are cited as of general interest. These references are U.S. Pat. No. 5,109,981 (Roy E. Maston lll et al.), issued May 5, 1992; U.S. Pat. No. 5,012,924 (Robert H. Murphy), issued May 7, 1991 and U.S. Pat. No. 5,108,299 (David V. Cronin), issued Apr. 28, 1992.
It is desirable to provide a shipping container or rail for a plurality of circuit packages which provides good protection against damage from electrostatic discharge, lends itself to convenient and efficient shipping and handling, and can be loaded and unloaded without damage or contamination from abrasion between circuit package and tubular container. Also desirable is a shipping container that can be loaded and unloaded by machine and is extremely inexpensive.